1. Field of the Invention
The present invention relates to improvements in light sensors, probes utilizing the sensors, communication with the sensor, and utilization of the information obtained from the sensor, specifically in real-time, operating-environment engine control and optimization in engines generating ultraviolet light with useful information, for example diesel engines. More particularly, the invention relates to improvements in integrated circuits and sensors in planar semiconductor processes including a silicon carbide lateral bipolar junction transistor that is monolithically integrated to create an ultraviolet sensor and pre-amplifier for further integration in very large scale integrated circuits. One use of the invention relates to the field of electronic sensors and controls for internal combustion engines and the development of digital real time homogenous charge compression ignition ultraviolet signature feedback for hydraulically actuated electronic unit injection, HEUI, engine optimization.
2. Description of the Known Art
As will be appreciated by those skilled in the art, light sensors, engine probes, and engine control systems are known in various forms.
For light sensors, silicon-based imaging technologies will absorb ultraviolet, visible and infrared photons and generate electron-hole pairs. If the application requires sensitivity only to ultraviolet light, costly steps must be taken to filter out the visible and infrared spectrum by using filtering optics or additional thin film processing.
In Silicon CMOS or Silicon CCD technologies, ultraviolet photons are absorbed very close to the silicon surface. Therefore, ultraviolet imagers must not have polysilicon, nitride or thick oxide layers that impede the absorption of ultraviolet photons. Modern ultraviolet imagers are hence backside thinned, most with only a very thin layer of Argon coating on top of the silicon imaging surface. Backside thinning drives up the cost of the ultraviolet imager, the associated packaging, and reduces mechanical reliability.
Although backside thinning is now ubiquitous in mobile imagers, ultraviolet response is not. To achieve a stable ultraviolet response, the imager surface requires special surface treatment, regardless of whether the imager is Silicon CMOS or Silicon CCD. Many backside-thinned imagers developed for visible imaging have thick oxide layers that can discolor and absorb ultraviolet after extended ultraviolet exposure. Some backside-thinned imagers have imaging surfaces that are passivated by a highly-doped Boron layer that extends too deep into the silicon epitaxy, causing a large fraction of ultraviolet photo-generated electrons to be lost to recombination.
Ultraviolet response and backside thinning are achievable in all line scan imagers, but not all area imagers. No global shutter area Silicon CCD can be backside thinned. The situation is better in Silicon CMOS area imagers, though still not without trade-offs. Silicon CMOS area imagers with rolling shutters can be backside thinned. Conventional Silicon CMOS global shutter area imagers have storage nodes in each pixel that need to be shielded when thinned, but only if these ultraviolet sensitive imagers will also be imaging in the visible spectrum. In backside-thinned area imagers, it is not possible to effectively shield part of the pixel from incident illumination, without severely degrading the imager's fill factor, the ratio of the light sensitive area to the total pixel area. There are other types of Silicon CMOS global shutter area imagers that do not have light sensitive storage nodes, but have higher noise, lower full well, rolling shutter, or a combination of these. Silicon also has a limited operating range typically above negative 40° C. and below 125° C.
In another field, the use of homogenous charge compression ignition, HCCI, in diesel engines produces an optical emission with an infrared, visible, and ultraviolet spectrum. The spectral response of this emission produces a unique photon signature that depends on fuel type, engine health, and evolution of pollutants in the combustion process. A portion of the optical signature can be transduced to an electrical signature by the emitted photons that have an energy greater than the excitation band-gap energy of a solid state semiconductor photo-detector. The state of the art is to capture this signature in a laboratory environment using optically accessible engines. The sensor electronics and signal processing used in the laboratory instruments are sensitive, bulky, and not suitable to real-time signal processing, thus preventing the use of the HCCI signature in practical engine control algorithms. More importantly these instruments require precise temperature management to improve the signal to noise ratio of the HCCI emission signature with respect to the back ground radiation of the engine block. These instruments also require complex optical filters and prisms to discriminate photons of different energies or wavelengths, for example, infrared, visible and ultraviolet wavelengths. Thus, the information gathered from these instruments is used to improve over-all design of diesel engines but is not applicable to the run-time operation of practical engines. The optical signature of the HCCI contains useful information such as the timing of the ignition, intensity, and duration of the combustion, the evolution of the combustion process, and engine health. As such, the optical signature is used in diesel engine diagnostic equipment. The required proximity of the light sensors in these diagnostic tools requires complicated procedures and short test times. Consequently less invasive diagnostic techniques involving measurement of exhaust and blow-back are more commonly used in evaluating engine health.
The HCCI optical signature has been correlated to the pressure signature through studies in HCCI heat release rate. Consequently, other solutions capture the pressure signature of the HCCI. Solutions using the pressure signature involve moving parts, such as deformable diaphragms and spring loaded systems and therefore suffer reliability issues. Consequently, reliable diesel engine design is limited to mechanical feedback systems such as flywheel sensors to control the timing of diesel fuel injection based only on crank angle, which severely limits the ability for run-time optimization of diesel engine performance.
Patents disclosing information of interest include: U.S. Pat. No. 3,504,181, issued to Chang, et al. on Mar. 31, 1970 entitled Silicon carbide solid state ultraviolet radiation detector;
U.S. Pat. No. 5,093,576, issued to Edmond, et al. on Mar. 3, 1992 entitled High sensitivity ultraviolet radiation detector;
U.S. Pat. No. 5,670,784, issued to Cusack, et al. on Sep. 23, 1997 entitled High temperature gas stream optical flame sensor;
U.S. Pat. No. 6,344,663, issued to Slater, Jr, et al. on Feb. 5, 2002 entitled Silicon carbide CMOS devices. Other publications include United States Patent Application 20060261876 A1, filed by Agarwal; Anant K. et al. on Nov. 23, 2006 entitled Optically triggered wide bandgap bipolar power switching devices and circuits. Each of these patents and publications are hereby expressly incorporated by reference in their entirety.
Other references teaching information that may be considered include:
“CCD vs. CMOS—Teledyne DALSA Inc.” [Online]. Available: http://www.teledynedalsa.com/imaging/knowledge-center/appnotes/ccd-vs-cmos/. [Accessed: 26 Aug. 2013].
R. Augusta, D. E. Foster, J. Ghanhi, J. Eng, and P. M. Najt, “Chemiluminescence Measurements of Homogeneous Charge Compression Ignition (HCCI) Combustion,” 1520-2006. [Online]. Available: http://papers.sae.org/2006-01-1520/. [Accessed: 11 Dec. 2013].
M. Jansons, A. Brar, F. Estefanous, R. Florea, D. Taraza, H. Nacim, and W. Bryzik, “Experimental Investigation of Single and Two-Stage Ignition in a Diesel Engine,” 1071-2008. [Online]. Available: http://papers.sae.org/2008-01-1071/. [Accessed: 11 Dec. 2013].
“Measurements of Thermal Stratification in an HCCI Engine | Combustion Research Facility.” [Online]. Available: http://crf.sandia.gov/index.php/measurements-of-thermal-stratification-in-an-hcci-engine/.UrRupxDt5rg. [Accessed: 20 Dec. 2013].
Snap-on Tools, “Snap-on MT1480A Gasoline & Diesel Engine Tack/Timing Meter User Manual.” Snap-on Tools, 1990.
“A QC Success Story With The Michigan Army National Guard's Diesel Engine Rebuilding Programme.” [Online]. Available: http://www.picoauto.com/applications/diesel-engine-rebuild.html. [Accessed: 20 Dec. 2013].
T. Yoshikawa and R. Reitz, “Effect of Radiation on Diesel Engine Combustion and Heat Transfer,” J. Therm. Sci. Technol., vol. 4, no. 1, pp. 86-97, 2009.
“Optrand Products.” [Online]. Available: http://www.optrand.com/products.htm. [Accessed: 23 Sep. 2013].
Motortechnischen Zeitschrift, “Beru Glow Plug Pressure Sensor.” [Online]. Available: http://www.beru.com/download/produkte/fachaufsatz_psg_en.pdf. [Accessed: 19 Dec. 2013].
CATERPILLAR, “Diesel Engine Control Systems Application and Installation Guide.” CATERPILLAR, 2008.
Each of these publications are also hereby expressly incorporated by reference in their entirety.
From these prior references it may be seen that these prior art patents are very limited in their teaching and utilization, and an improved sensor, probe, communication system, and engine control system are needed to overcome these limitations.